Valve device

ABSTRACT

The invention relates to a valve device for a hydraulic circuit ( 10 ), which valve device divides the incoming volume flow into at least two pre-determined partial flows for supplying hydraulic consumers (V 1 , V 2 ) of the circuit ( 10 ), which valve device has at least one pressure balance ( 16 ) and at least one orifice. As a result of the fact that the orifice is embodied as a variable orifice ( 32 ) which can be controlled by means of a proportional magnet ( 34 ) in such a way that the opening area of said orifice varies, a type of flow regulator is realized which can switch the regulated volume flow and/or proportionally adjust the regulated volume flow in a defined manner.

The invention relates to a valve device for a hydraulic circuit which divides the incoming volumetric flow into at least two predetermined partial flows for the supply of hydraulic consumers of the circuit, where said valve device has at least one pressure compensator and at least one orifice.

These valve devices are also referred to as flow regulators or pressure-compensated flow control valves in the technical jargon and allow the incoming volumetric flow to be divided into a regulated and an unregulated residual volumetric flow according to the throttle principle. Ultimately, they are throttle valves with an adjustable orifice (throttle) in which the flow rate remains constant, regardless of changing load pressures, by a combination with a respective pressure compensator. At the same time, the pressure compensator clears a changing cross section that is inversely proportional to the load pressure so that consequently the flow rate remains essentially constant, regardless of the load pressure.

Such a valve device is shown, for example, in DE 10 2006 004 264 A1, which relates to a stabilization means for a multi-axle vehicle with one hydraulic control circuit each provided for the front and the rear axles. Because in the known solution the incoming volumetric flow of at least one of the axles is controlled by the pressure-compensated flow control valve, and because at a higher capacity of the supply unit, the accompanying excess of volumetric flow can be relayed to at least one of the other axles which is unregulated, in case of an excess of the volumetric flow, the latter is kept constant on the axle controlled by means of the flow control valve, and the excess portion travels to the respective unregulated axle. Among other things, this causes the desired roll stabilization on the unregulated axle in terms of trigger behavior to be designed to be more highly dynamic; under actual driving conditions, this confers distinct advantages compared to otherwise conventional divisions of amounts with percentage volumetric ratios that are stipulated in a defined manner for the respective partial flow amounts for the supply of the hydraulic consumers in the form of the control circuit for the indicated front and rear axles.

Proceeding from this prior art, the object of the invention, regardless of how high the power demand is for the respective partial flow of the hydraulic circuit, is to supply with the necessary amount of fluid that consumer that has to ensure the power demand for a safety-relevant system of the hydraulic circuit. This object is achieved by a valve device with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the orifice is outfitted as a variable orifice which can be triggered by means of a proportional magnet such that its opening area can be changed, a type of flow regulator is implemented which can switch and/or proportionally set the controlled volumetric flow in a defined manner. This function is required, in particular, when at least two hydraulic systems are operated with hydraulic consumers that are different in terms of power demand by only one hydraulic pump as a pressure supply source and their power demand can be at least in part very different, while at the same time one of the two systems comprises the safety-relevant system which must be supplied under all conditions.

Owing to the variable orifice which is implemented by triggering with a proportional magnet, consequently, a proportionally variable opening area arises which is made such that for all trigger states a defined passage area remains opened which, in any case, covers the power demand for the safety-relevant system. Even in the case of a fault, if therefore, for example, the power for the proportional magnet as a trigger means fails, a maximally regulated volumetric flow is supplied to the safety-relevant system and its operation is guaranteed.

The valve device according to the invention, which is designed in this respect as a variable pressure-compensated flow control valve, is especially advantageous when used in vehicles of any type (passenger cars, busses, trucks, roadworthy machinery, etc.) where a hydraulic pump driven by the vehicle engine as a pressure supply source supplies both the servo-assisted steering and also the roll stabilization for the axles of the vehicles.

For the associated power demands on the individual systems, this means the following based on practical circumstances.

When the vehicle is driving at speed, only very little steering deflection (speed) is necessary on the part of the operator, and in this respect little servo assistance is necessary. In this case, the volumetric flow in the steering circuit can be ramped down to a minimum value, while at the same time greater roll moments must be corrected. Conversely, when parking, for example, a large steering deflection (speed) with correspondingly high servo assistance is necessary, and roll compensation is less important when parking. For both system requirements, however, there should never be too little volumetric flow for the steering since otherwise the servo assistance for the steering deflection will fail, and modern vehicles are very difficult to manage with normal expenditure of force without the pertinent servo assistance. With the solution according to the invention, for this application it is always ensured that steering does not receive too little volumetric flow relative to the indicated servo assistance.

It must also be ensured, in case of a fault, that, for a minimally regulated volumetric flow, servo assistance benefits the steering system. Furthermore, when the power fails, as another possible fault source for the proportional magnet, the latter should then set the largest opening area on the orifice and the largest regulated volumetric flow will be available for steering.

Regardless of the described application, the valve device according to the invention can always be used wherever different partial flows of a hydraulic circuit must be set with connected hydraulic consumers which have different power requirements and/or which, especially for safety reasons, are not to be supplied beforehand.

If in this application text the expression “orifices” is used, this term is intended to also describe and at the same time to cover the use of “throttles.” This also applies to the term “metering orifice” used technically below. To the extent that the expression “orifice,” “variable orifice,” “free orifice cross sections,” etc. are used, these generally include the terms “throttle,” “variable throttle,” “free throttle cross-sectional area,” etc.

In one especially preferred embodiment of the valve device according to the invention, at least the pressure compensator and the respectively used orifices and proportional magnet are components of a common valve block which in this respect can also be retrofitted on site onto existing vehicle systems as a modular unit.

Other advantageous embodiments of the valve device according to the invention are the subject matter of the other dependent claims.

The valve device according to the invention is detailed below using exemplary embodiments as shown in the drawings. The figures are schematic and not to scale.

FIG. 1 shows the basic structure of the valve device using a hydraulic circuit diagram;

FIG. 2 shows, as a longitudinal section, but without the crosshatching, the proportional magnet used in the valve device with a connected valve housing for implementation of a variable orifice and a constant orifice;

FIG. 3 shows the valve device as shown in FIG. 2 with a downstream pressure compensator in addition to a damping means;

FIG. 4 shows a pressure compensator corresponding to FIG. 3, but without additional vibration damping;

FIG. 5 shows, in a perspective top view, the valve device as a whole.

The valve device, which is shown in FIG. 1 as a hydraulic circuit diagram, is used to supply a hydraulic circuit 10 with fluid. The hydraulic circuit 10 is supplied with fluid by way of a pressure supply source 12. The pressure supply source 12 has a conventional hydraulic pump which can be driven by an engine, for example the internal combustion engine of a motor vehicle. The volumetric fluid flow, which is flowing in via the line 14 from the pressure supply source 12, is divided at the branch site X, one partial flow leading to a hydraulic consumer V₁, which is not detailed, and the other partial flow to a hydraulic consumer V₂. In the specific exemplary embodiment, the consumer V₁ is designed to be formed from the servo-assisted steering system, and the consumer V₂ forms a roll stabilization system for the axles of the indicated vehicle (not shown).

Furthermore, the valve device has a conventional pressure compensator 16, which is shown in the non-regulating basic position and otherwise forms a type of 4/3-way proportional valve solution. The pressure compensator spool 20, guided in the pressure compensator housing 18, is exposed on its opposite sides to control pressures ST₁ and ST₂, which act in opposite directions, and furthermore, viewed in the direction of looking at FIG. 1, the pressure compensator spool 20 with its right side is supported on an adjusting spring 22 in the manner of a compression spring. One control pressure ST₂ is connected to the branch site X, which in turn is connected to the fluid inlet E₂ of the pressure compensator 16 to carry fluid via the line 24. The other control pressure ST₁ is tapped upstream of the inlet E₁ of the pressure compensator 16 in the supplying line 26. Furthermore, this line 26 leads to a branch site X. Accordingly, on the opposite side, there are the fluid outlets A₁, A₂ which are connected by way of lines 28, 30 to the first hydraulic consumer V₁ and second consumer V₂.

Beginning at the branch site X, a variable orifice 32 is connected to the line 26 and can be triggered by means of the proportional magnet 34, i.e., the free opening area of the variable orifice 32 can be dictated by means of the proportional magnet 34. Parallel to the variable orifice 32 another orifice 36 is connected as a so-called constant orifice, i.e., the free opening area of the other orifice 36 is constant. The indicated parallel arrangement for the other orifice 36 arises from its being connected to a line 38 which, viewed in the fluid direction, discharges upstream of the variable orifice 32 into the line 14, and downstream of the variable orifice 32 into the line 26, specifically, at the connecting site 40. Furthermore, as shown in FIG. 1, the line 38 discharges into the branch site X of the line 14. Moreover, to obtain the control pressure ST₁, the pressure compensator 16 is connected by way of the control line, indicated by the broken line, to the line 26 between the connecting site 40 and the fluid inlet E₁ so that, accordingly, the fluid pressure prevailing at E₁ is present as the control pressure ST₁ and the control pressure ST₂ is the fluid pressure on the fluid inlet side E₂ of the pressure compensator 16. This control line for the control pressure ST₂ is also shown in FIG. 1 by the broken line.

To trigger the whole system, the coil winding 42 of the proportional magnet 34 is connected to a computer unit, which is not detailed, by way of an electrical plug contact 44 (cf. FIG. 2) which, for example, depending on the driving speed of the vehicle, dictates the trigger values of the current for the proportional magnet 34. Overall, with the solution as shown in FIG. 1, a valve device in the manner of a flow regulator is devised which can proportionally set in a defined manner the regulated partial volumetric flow to the consumer which is to be regulated. This function is required if, proceeding from the pressure supply source 12, for example two hydraulic systems with a consumer V₁ (servo-assisted steering system) and a consumer V₂ (roll stabilization system) are operated whose power demands to some extent are distinctly different. At the same time, one of the two systems, specifically the servo-assisted steering system, is a safety-relevant vehicle system and must be supplied with the volumetric flow which is necessary for safe operation under all conditions. The valve representation as depicted in FIG. 2 shows the energized and therefore connected state for the valve device, yielding a minimum volumetric flow.

Then, in particular, the following applies to the power requirements of the two systems:

When the vehicle is driving at speed, only very little steering deflection (speed) is necessary and, accordingly, little servo assistance is required. In this case, the regulated volumetric flow in the steering circuit can be ramped down for the consumer V₁ to a minimum value; this is induced by the proportional magnet 34, which can be triggered depending on the speed. In turn, larger roll moments must be corrected and the consumer V₂ acquires a larger residual volumetric flow from the branch site X and the pressure compensator 16. By contrast, when parking, for example, a large steering deflection (speed) with high servo assistance is necessary, so that the hydraulic consumer V₁ requires a large partial volumetric flow. Roll compensation is conversely less relevant during parking, so that the fluid volumetric flow required in this respect can be reduced.

For both described states, however, the steering system, i.e., the hydraulic consumer V₁, should never receive too little volumetric flow; this is achieved with a valve device as shown in FIG. 1. In the case of a fault, i.e., for example when the power fails, the proportional magnet 34 is no longer energized, and it is ensured that the variable orifice 32 will assume its largest opening cross section, i.e., have the largest opening area, and thus the largest regulated volumetric flow will continue to travel to the servo-assisted steering system (consumer V₁).

In the valve device according to the invention, the arrangement of the proportional magnet 34 with a variable orifice 32 and constant orifice 36 is detailed below. As already described, the proportional magnet 34 has a coil winding 42 which can be triggered by way of an electrical plug contact 44 by a computer unit (on-board computer), not shown, which processes the vehicle-side data, such as, for example, the vehicle speed, steering deflection, etc. In a pole tube arrangement 46 with magnetic separation 48, an armature body 50 with an actuating rod 52 which is inserted on the end side is guided to be able to move lengthwise. The proportional magnet 34 is made as an attachment part, and the magnet housing 54 can be fixed on third components by way of a flange part 56, for example in the form of a valve block 58 as shown in FIG. 5. By way of the electrical contact 44 the coil winding 42 can be triggered by means of the aforementioned computer unit which, depending on the vehicle speed, in turn relays control pulses to the coil winding 42, which advances the armature body 50 with the actuating rod 52. The structure of these proportional magnets 34 is known so that it will not be further detailed here.

The proportional magnet 34 is connected to a valve housing 60 in which a valve spool or control spool 62 is guided. The control spool 62 on its right side, viewed in the direction of looking at FIG. 2, is triggered by the actuating rod 52 and is supported with its other left free end on a support spring 64 in the manner of a compression spring which is supported in the valve housing 60 by way of a plug 66 and applies a permanent resetting compressive force to the control spool 62. Furthermore, the control spool 62 has an annular widening 68, and on its left free face side it has a conically widening control surface 70.

The pertinent surface 68 is used to trigger passage openings 72, 74. The indicated passage openings are made as passage bores and arranged in succession to one another and, preferably diametrically opposite one another, extend repeatedly through the valve housing 60. Furthermore, the passage openings 72, 74, viewed in each cross-sectional row, can have different diameters and/or a different number of holes. In particular, FIG. 2 shows a first row of bores with passage openings 72, 74 which are arranged in succession viewed in the direction of travel of the control spool 62, the first row of passage openings 72 in concert with the annular widening 68 of the control spool 62 forming the control for the variable volumetric flow portion and therefore forming the orifice design for the variable orifice 32; conversely, the constant orifice 36, which is located in the bypass and in a parallel connection, is formed by the passage opening 74. The variable orifice 32 is therefore formed by the passage opening 72 and the constant orifice 36 by the passage opening 74.

Depending on the position of the control spool 62, the latter then regulates the variable orifice 32 by way of the corresponding control edge between the passage opening 72 and the cylindrical constriction 78 in the control spool 62. FIG. 2 also illustrates that, in the event of a power failure and in the event the coil winding 42 is no longer energized, the support spring 64 is relieved and, viewed in the direction of looking at FIG. 2, shifts the control spool 62 to the right; this leads to complete opening of the passage openings 72, 74, and fluid passage is such that a regulated fluid supply is ensured by way of the connecting site 40 for the partial fluid circuit relating to the consumer V ₁ in the form of the servo-assisted steering. In this way, a type of fail-safe circuit is achieved for the valve device according to the invention.

With the valve solution as shown in FIG. 2, a variable metering orifice (throttle) 32 is implemented which is characterized by triggering with the proportional magnet 34 and consequently with a proportionally variable opening area, formed by the passage opening 72. This variable opening area is designed such that for all trigger states a defined area always remains open by means of the proportional magnet 34. Here, it would be fundamentally sufficient in one basic version to provide only one row of passage openings 72 for fluid passage from the outside to the inside, where, to limit the stroke of the control spool 62, it has to be ensured that at least part of the hole diameter which is active in this respect then remains free.

It has been shown in practice, however, that with a solution with only one row of bores which is only partially closed, it is difficult to ensure exact adjustment of the volumetric flow in the energized end position of the magnet 34. In particular, tolerances cannot be allowed in production and mounting. Conversely, a reliable and durable system can be achieved with an arrangement in which, in addition to the proportionally adjustable orifice (throttle) 32, there is an orifice (throttle) 36 which is always open. The constant orifice 36 is connected parallel to the proportionally adjustable orifice 32 so that the overall orifice ratio for the system at the connecting site 40 for the pressure compensator 16 is the product of the sum of the two opening cross sections or opening areas.

To be on the safe side, the control spool 62 for the variable orifice 32 is dimensioned such that it is approximately 0.1 mm in front of the assignable row of passage openings 72 in the unenergized state and, in the fully energized state, viewed in the direction of looking at FIG. 2, is 0.1 mm to the left following the row of passage openings 72. This structural design, which is only exemplary, ensures that, regardless of the production tolerances, the variable orifice 32 can in any case be completely opened or closed. In this respect, defined conditions prevail and the end values are reliably reached. The permanently open orifice 36 can be implemented in the valve block 58 (FIG. 1) or, as shown in FIG. 2, as a second row of bores 74 which preferably cannot be crossed in its entirety or even partially by the valve spool or control spool 62, depending on the application.

The variable orifice 32 always interacts with the pressure compensator 16 which is connected downstream in the fluid direction; this is detailed in FIG. 3. The pressure compensator 16 is designed as a screw-in cartridge solution, and, as shown in FIG. 4, can be inserted into a valve block 58 (compare the exemplary embodiment as shown in FIG. 5). Thus, viewed in the direction of looking at FIG. 3, on the left side, there is a screw-in part 80 and on the opposite right side another screw-in part 82, the other screw-in part 82 in the housing 18 of the pressure compensator 16 also being used to set the spring pretensioning for the adjusting spring 22 since regulation is to take place exactly to a small Δp. In agreement with the basic circuit diagram as shown in FIG. 1, on the pressure compensator the individual connections are designated as E₁, E₂, A₁, and A₂. Furthermore, in the embodiment as shown in FIG. 3, at one other branch site 84 within the lines 24, 26 in the secondary branch 86, part of the pertinent partial volumetric flow is routed as the control flow ST₁, ST₂ from the inlet side E₁, E₂ of the pressure compensator 16 to the assigned end side 88 of the pressure valve spool 20. In this respect the pressure compensator spool 20 in each of its positions of travel has a fluid-tight separation between the inlet sides E₁ and E₂ to the spool end sides 88 by means of the spool ring surfaces 90 adjoining the pressure compensator housing 18. Furthermore, one identical damping orifice 92 at a time is connected to the indicated secondary branch 86. With these damping orifices 92 in the bypass, unwanted oscillations in the operation of the pressure compensator 16 can be avoided. The respective damping orifices 92 can also be implemented in the form of damping bores in the pressure compensator housing 18. It would also be possible to provide only one of the two sides of the pressure compensator 16 with damping.

As depicted in FIG. 3, the pressure compensator spool 20 is shown in its middle actuation position in which it partially overlaps the fluid outlets A₁, A₂ which lead to the hydraulic consumers V₁ and V₂. The fluid inlets E₁ and E₂ conversely are left open by the spool 20 and, by way of radial recesses 96, there is a permanent fluid connection between E₁, A₁ and E₂ with A₂, the fluid outlets A₁, A₂ respectively being choked by the pressure compensator spool 20. Depending on the position of travel of the pressure compensator spool 20, the fundamental switching possibilities for the pressure compensator 16 as shown in FIG. 1 are achieved analogously. Since this pressure compensator structure is inherently known, it will not be further detailed here.

The embodiment as shown in FIG. 4 has been altered compared to the other embodiment, as shown in FIG. 3, in that the damping orifices 92 are omitted. The pressure compensator spool 20 in this embodiment in each of its positions of travel also has spool ring surfaces 90 which are spaced apart from the pressure compensator housing 18. Otherwise, in terms of surface ratio, the spool ring surfaces 90 opposite one another correspond to one another for the embodiments as shown in FIGS. 3 and 4, so that in this respect for both embodiments the spool 20 is essentially symmetrical in design. In the modified embodiment as shown in FIG. 4, the fluid travels via the inlets E₁, E₂ as well as the radial recesses 96 and the respective annular gap 98 to the active spool ring surface 90.

As the valve block configuration according to FIG. 5 shows, the entire valve device can be combined in one unit. For purposes of a compact arrangement, it is preferably provided that the proportional magnet 34 projects on the top of the valve block 58 and is fixed there by means of the flange 56. Then the valve housing 60 with the different passage sites to the orifice formation 32, 36 projects into the valve block 58. Transversely to this installation arrangement, the pressure compensator 16, viewed in the direction of looking at FIG. 5, then extends essentially in the horizontal position between the free end sides of the valve block 58, and in this case the screw-in parts 80, 82 form the housing termination to the outside. Then the important connecting lines P, A₁, and A₂ discharge on the side of the valve block 58 facing the viewer of FIG. 5. Other block arrangements are possible. 

1. A valve device for a hydraulic circuit (10) which divides the incoming volumetric flow into at least two predetermined partial flows for the supply of hydraulic consumers (V₁, V₂) of the circuit (10), which valve device has at least one pressure compensator (16) and at least one orifice, characterized in that the orifice is designed as a variable orifice (32) which can be triggered by means of a proportional magnet (34) such that its opening area can be changed.
 2. The valve device according to claim 1, characterized in that another orifice (36) with a preferably constant opening area is connected parallel to the variable orifice (32).
 3. The valve device according to claim 2, characterized in that in a valve housing (60) assigned to the proportional magnet (34) there is at least one first row of bores with at least two passage openings (72, 74) that are arranged in succession in the direction of travel of the control spool (62), which control spool can be moved within the valve housing (60) by means of the proportional magnet (34).
 4. The valve device according to claim 3, characterized in that the control spool (62) varies at least one free opening area of the passage openings (72, 74) which are located in succession in the valve housing (60).
 5. The valve device according to claim 3, characterized in that the first row of bores (72, 74) in the valve housing (60) is connected to a pressure supply source (12) and that the respectively other passage opening (76) is connected to at least one fluid inlet (E₁) of the pressure compensator (16) to carry fluid.
 6. The valve device according to claim 5, characterized in that at the branch site (X) of the hydraulic circuit (10) a partial flow of the volumetric fluid flow is supplied to the valve housing (60) of the proportional magnet (34) by way of the first row of holes (72, 74) and the second partial flow is supplied at least to one other fluid inlet (E₂) of the pressure compensator (16).
 7. The valve device according to claim 6, characterized in that at one further branch site (84) at a time in the secondary branch, part of the partial volumetric flow is routed on the inlet side (E₁, E₂) of the pressure compensator (16) to the assigned spool end side (88) of the pressure compensator spool (20).
 8. The valve device according to claim 7, characterized in that the pressure compensator spool (20) in each of its positions of travel separates the inlet sides (E₁, E₂) fluid-tight from the spool end sides (88) by means of the spool ring surfaces (90) which adjoin the pressure compensator housing (18) and that a damping orifice (92) is connected in at least one secondary branch (86).
 9. The valve device according to claim 7, characterized in that the pressure compensator spool (20) in each of its positions of travel produces a fluid-carrying connection between the inlet sides (E₁, E₂) and the spool end sides (88) which can be assigned to the latter by means of the spool ring surfaces (90) which are spaced apart from the pressure compensator housing (18).
 10. The valve device according to claim 1, characterized in that at least the pressure compensator (16) and the respectively used orifices (32, 36) and proportional magnet (34) are components of a common valve block (58). 